Functional brain response pattern under rubber hand illusion based on fNIRS.

The rubber hand illusion (RHI), where people experience a sense of ownership over a rubber hand, has been researched by various neuroimaging methods. Here we used functional near-infrared spectroscopy (fNIRS) to analyze the activation and functional connectivity of related brain regions under RHI. Meanwhile, three brain functional network parameters were calculated and analyzed: degree, clustering coefficient, and characteristic path length. fNIRS results showed that under RHI, the oxyhemoglobin (HbO) concentration increased in the prefrontal cortex (PFC), motor cortex (MC) and occipital lobe (OL). The functional connectivity between right PFC and bilateral OL was increased, while the connection level between left MC and bilateral OL was decreased. Brain network under RHI condition had smaller average degree, average clustering coefficient, and shorter average characteristic path length. Notably, the information processing and exchange functions of left MC seem to be weakened under RHI state, which was also partially corroborated by the reduced local efficiency shown in brain functional network analysis. Overall, we suggest that enhanced functional connectivity between the right MC, OL and PFC, and functional inhibition of the left MC were key to RHI production. The study significance lies in enhancing understanding of body ownership and sensory integration.